Invasion of vascular cells into tissues requires the coordinated interplay of numerous factors including proteinases, which remodel the extracellular matrix architecture, as well as cell adhesion molecules that recognize this provisional matrix. Recent reports have implicated that the 72 kDa matrix metalloproteinase 2 (MMP2) is a key player in vascular development and angiogenesis. For example, Kitoh et al. (J. Cell Sci., 109, 953-8 (1996)) report that MMP2 and its activator membrane type 1-matrix metalloproteinase (MT1-MMP) are coordinately expressed by mesenchymal cells almost exclusively during embryonic development, indicating specific matrix remodeling constraints in these tissues. In addition, angiogenesis and corresponding tumor growth are reduced in MMP2 knockout mice (see Itoh et al., Cancer Res., 58 1048-51 (1998)). Interestingly, Saftor et al. (Proc. Natl. Acad. Sci. U.S.A., 89, 1557-61 (1992)) have shown that ligation of the integrin αvβ3, itself a known mediator of angiogenesis, induces MMP2 production, suggesting a coordinated interplay of these two molecules during the vascular remodeling associated with blood vessel formation (see also Bafetti et al., J. Biol. Chem., 273, 143-9 (1998)). In fact, direct interaction between MMP2 and integrin αvβ3 has been demonstrated by Brooks et al. (Cell, 85, 683-93 (1996)). The negative regulation of MMP2 during vascular invasion and maturation was later shown by Brooks et al. to be dependent upon expression of αvβ3 (Cell, 92, 391-400 (1998)).
Although inhibition of angiogenesis and concomitant suppression of tumor growth by natural as well as synthetic inhibitors of MMP's, including MMP2, has been documented, the translation of such strategies into clinical modalities has met with limited success, primarily due to the deleterious side effects of such broad spectrum inhibitors. Since MMP function, in general, may be required for many processes in the adult organism, active site inhibition of enzymatic function is likely to have far reaching effects on various biological processes involving tissue remodeling, such as wound healing. In fact, it has been documented that therapies with broad spectrum MMP inhibitors in clinical studies of various cancer types cause severe side effects, including inflammatory tendinitis, polyarthritis, and muscoskeletal pain syndromes, which are dose limiting and often persist after discontinuation of therapy. Given the limited distribution of integrin αvβ3 in adult organisms, however, one would predict that targeting the interaction between MMP2 and αvβ3 to the areas of neovascularization or cellular invasion should correspondingly limit the effects of such treatment-related toxicities. Indeed, the recombinant non-catalytic carboxy-terminal hemopexin domain of MMP2 (PEX), which mediates MMP2 binding to integrin αvβ3, has shown antiangiogenic and antitumor activity in vivo. The potential utility of such a large protein fragment, but with attendant shortcomings (e.g. large scale production problems, FDA quality and safety control issues and antigenicity), suggested the need for a more practical solution to this problem.
There is a need therefore, for methods of inhibiting angiogenesis and tumor growth utilizing chemical compounds that selectively inhibit MMP activity at tumor growth sites with minimal inhibition of MMP in other regions of the body. There is also a need for methods of specifically binding to the MMP2 binding site of integrin αvβ3.